Thallium

A comprehensive overview of thallium, its properties, uses, and health effects

Thallium

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Thallium is a soft, malleable metal.

Thallium is a chemical element with the symbol Tl and atomic number 81. It is a soft, malleable metal that can be cut with a knife. Thallium is found in trace amounts in the Earth's crust and is primarily obtained as a byproduct of refining heavy metal sulfide ores.

Properties

Thallium is a post-transition metal that exhibits a bluish-gray hue. It is highly reactive and tarnishes when exposed to air, forming a dull oxide layer. Thallium is known for its high density and low melting point, which is 304 °C (579 °F). It is also diamagnetic and has a relatively low electrical conductivity compared to other metals.

Occurrence and Production

Thallium is not found free in nature. It is typically extracted from minerals such as crookesite, lorandite, and hutchinsonite. The primary method of obtaining thallium is through the processing of lead and zinc ores, where it is recovered as a byproduct. The metal is also found in trace amounts in coal and is released into the environment during coal combustion.

Uses

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Thallium iodide is used in high-intensity discharge lamps.

Thallium has several industrial applications due to its unique properties. It is used in the production of electronic devices, optical lenses, and low-temperature thermometers. Thallium sulfate, a compound of thallium, was historically used as a rodenticide and insecticide, although its use has been largely discontinued due to its toxicity.

Thallium iodide is used in high-intensity discharge lamps, which are employed in street lighting and projectors. These lamps produce light with excellent color rendering properties.

Health Effects

Thallium is highly toxic and poses significant health risks. It can be absorbed through the skin, inhaled, or ingested. Thallium poisoning can lead to symptoms such as hair loss, nerve damage, and organ failure. Due to its toxicity, thallium compounds are handled with extreme caution in industrial settings.

Safety and Regulations

Due to its toxicity, the use of thallium is strictly regulated in many countries. Safety measures include the use of protective equipment and proper ventilation in workplaces where thallium is present. Environmental regulations also limit the release of thallium into the environment to prevent contamination of water and soil.

Related pages

• Periodic table
• Heavy metals
• Toxicology
• Industrial safety